Method of obtaining a combination of Z and E stereoisomers of hydrofluoroolefins

ABSTRACT

Disclosed are the combinations containing Z and E stereoisomers of hydrofluoroolefins where the more toxic isomer is less than about 30% weight of the combination (vs the sum of Z+E), to minimize the toxicity impact in the applications they will be used for such as cooling and heat fluids, foams blowing agents or solvents. Also disclosed are means to obtain combinations containing Z and E stereoisomers of hydrofluoroolefins.

The present application is a divisional application of U.S. applicationSer. No. 12/667,115 filed Dec. 29, 2009; and International applicationserial number PCT/US08/75165 filed Sep. 4, 2008 which designated theUnited States; and U.S. provisional application Ser. No. 60/972,037filed Sep. 13, 2007.

FIELD OF THE INVENTION

The present invention relates to compositions containing a combinationof Z and E stereoisomers of hydrofluoroolefins. The present inventionalso relates to means to obtain the compositions. The compositions ofthe present invention are useful in processes for producing cooling orheat, as heat transfer fluids, refrigerants, foam blowing agents,aerosol propellants, fire suppression, extinguishing agents and solventapplications for metal degreasing and dewatering agent.

BACKGROUND OF THE INVENTION

The Montreal Protocol for the protection of the ozone layer, mandate thephase out of the use of chlorofluorocarbons (CFCs). Materials more“friendly” to the ozone layer, such as hydrofluorocarbons (HFCs) egHFC-134a replaced chlorofluorocarbons. The latter compounds have provento be green house gases, causing global warming and were regulated bythe Kyoto Protocol on Climate Change. The emerging replacementmaterials, hydrofluoropropene, were shown to be environmentallyacceptable ie has zero ozone depletion potential (ODP) and acceptablelow GWP.

Currently proposed replacement refrigerants for hydrofluorocarbons suchas HFC-134a include HFC-152a, pure hydrocarbons such as butane orpropane, or “natural” refrigerants such as CO₂. Many of these suggestedreplacements are, flammable, and/or have low energy efficiency.Therefore, new alternative refrigerants are being sought. Fluoroolefinmaterials such as hydrofluoropropene have generated interest asreplacements for HFCs. The inherent chemical instability of thesematerials in the lower atmosphere provides the low global warningpotential and zero or near zero ozone depletion properties desired.However, such inherent instability is believed to also impact theirtoxicity. In particular, the Z isomer will be much more active towardsoxygen compared to the E isomer.

The object of the present invention is to provide novel compositionsthat can serve as refrigerant and heat transfer fluids as well asblowing agents, solvent cleaners etc. that provide uniquecharacteristics to meet the demands of low or zero ozone depletionpotential, lower global warming potential and low toxicity.

SUMMARY OF THE INVENTION

The present invention is directed toward combinations containing Z and Estereoisomers of hydrofluoroolefins where the more toxic isomer is lessthan 30% weight of the combination (vs the sum of Z+E), to minimize thetoxicity impact in the applications they will be used for such ascooling and heat fluids, foams blowing agents or solvents. The inventionis also directed toward means to obtain these combinations.

DESCRIPTION OF THE INVENTION

Hydrofluoroolefins have been proposed as heat transfer fluids as well asblowing agents, solvent cleaners etc. which exhibit a low global warmingpotential and zero ozone depletion value. The low global warmingpotential is a result of the atmospheric degradation of thehydrofluoroolefins, typically in just a few days. The fast atmosphericdegradation of hydrofluoroolefins is related to reactivity with OHradicals.

Toxicity of hydrofluoroolefins varies between the geometric isomers.Hydrofluoroolefins, which can exist as Z and E isomers are of particularinterest include:

F1225 ye (1,2,3,3,3-pentafluoropropene) (Z and E isomers) and

F1234 ze (1,3,3,3-tetrafluoropeopene) (Z and E isomers)

F1233zd (1-chloro-3,3,3-trifluoropropene) (Z and E isomers)

From a reactivity point of view, the more sterically hindered isomer isbelieved to be more reactive and therefore likely more toxic. Apreferred ratio of Z and E isomers is less than about 30% weight of thecombination of the more toxic isomer (vs the sum of Z+E) and even morepreferably less than about 10% of the more toxic isomer. The mostpreferred ratio is less than about 1% of the more toxic isomer (vs thesum Z+E).

For F1225 ye (1,2,3,3,3-pentafluoropropene), a preferred ratio of Z andE isomers is less than about 30% weight of the combination of the Eisomer (vs the sum of Z+E) and even more preferably less than about 10%of the E isomer. The most preferred ratio is less than about 1% of the Eisomer (vs the sum Z+E).

For F1234 ze (1,3,3,3-tetrafluoropeopene), a preferred ratio of Z and Eisomers is less than about 30% weight of the combination of the Z isomer(vs the sum of Z+E) and even more preferably less than about 10% of theZ isomer. The most preferred ratio is less than about 1% of the Z isomer(vs the sum Z+E).

For F1233zd (1-chloro-3,3,3-trifluoropropene a preferred ration of Z andE isomers is less than about 30% weight of the combination of the Zisomer (vs. the sum of Z+E) and even more preferably less than about 10%of the Z isomer. The most preferred ratio is less than about 1% of the Zisomer (vs. the sum Z+E).

The combinations of the present invention can also further includeadditional low global warming potential and low or zero ozone depletionvalue materials including but not limited to hydrocarbons such aspentane or cyclopentane, CO₂, hydrofluorocarbons such as difluoromethane(HFC-32), 1,1,1,3 tetrafluoroethane (HFC-134a), pentafluoroethane(HFC-125) and 1,1-difluoroethane (HFC-152a); and hydrochloroalkenes suchas t-1,2-dichloroethylene (1,2-DCE).

Different technologies can be used to separate stereoisomers to obtainthe combinations of the present invention:

-   -   Distillation, when boiling points of isomers are sufficiently        different    -   Reactive distillation based on the difference of reactivity of        the isomers vs hydrogenation on chlorination (but not limited to        that) followed by distillation of the products of reaction    -   Catalytic isomerization of Z isomers to F isomers using a strong        Lewis acid such as SbF₅ and a high surface area fluorinated        alumina or activated carbon catalyst    -   Extraction or extractive distillation with a third solvent,        based of the difference of affinity of the isomers vs the        solvent, the third solvent could be but is not limited to        chlorinated C1, C2 and C3 solvents (CC14, CC13H, CH2C12,        CHC12-CHC12, CC13-CH3, CC12=CC12, CHC1=CHC1, CHC1=CC12 . . . ),        fluorinated or perfluorinated solvents (HFC, Hydrofluoroethers,        PFC), oxygenated solvents such alcohols or ethers, N containing        solvents such as amines, C1 to C10 hydrocarbons such as        isobutane, butane, propane, pentane, isopentane hexane . . . .    -   Separation on solids beds based on difference of absorption of        each isomer, the solids could be (but are not limited to)        molecular sieves, alumina, carbon sieves, zeolites and the like.    -   Membrane separation technology, which allow for the selective        passage of one isomer and retaining the other isomer.

1. Mobil Air Conditions (MAC) and Other Refrigerant Applications:

For MAC applications the preferred boiling point (bp) of the low GWPrefrigerants is between −10 to −40° C. Refrigerant must be chemicallystable during applications eg, doesn't react with active metal in thesystem such as aluminum, copper or iron, soluble and compatible withrefrigerant oil.

The combinations containing Z and E stereoisomers of hydrofluoroolefinsof the present invention have been found effective as replacements forhigh GWP (global warming potential) refrigerant in refrigeration,air-conditioning, or heat pump systems. Conventional high GWPrefrigerants in such systems include materials such as R134a, R22,R245fa, R114, R236fa, R124, R410A, R407C, R417A, R422A, R507A, andR404A. The combinations containing Z and E stereoisomers ofhydrofluoroolefins of the present invention are effective working fluidsin refrigeration, air-conditioning, or heat pump apparatus that uses,used or is designed to use conventional high GWP refrigerants.

Vapor-compression refrigeration, air-conditioning, or heat pump systemsinclude an evaporator, a compressor, a condenser, and an expansiondevice. A vapor-compression cycle re-uses refrigerant in multiple stepsproducing a cooling effect in one step and a heating effect in adifferent step. The cycle can be described simply as follows: liquidrefrigerant enters an evaporator through an expansion device, and theliquid refrigerant boils in the evaporator at a low temperature to forma gas and produce cooling. The low-pressure gas enters a compressorwhere the gas is compressed to raise its pressure and temperature. Thehigher-pressure (compressed) gaseous refrigerant then enters thecondenser in which the refrigerant condenses and discharges its heat tothe environment. The refrigerant returns to the expansion device throughwhich the liquid expands from the higher-pressure level in the condenserto the low-pressure level in the evaporator, thus repeating the cycle.

As used herein, mobile refrigeration apparatus or mobileair-conditioning (MAC) apparatus refers to any refrigeration orair-conditioning apparatus incorporated into a transportation unit forthe road, rail, sea or air. The present invention is particularly usefulfor road transport refrigerating or air-conditioning apparatus, such asautomobile air-conditioning apparatus or refrigerated road transportequipment.

The combinations containing Z and E stereoisomers of hydrofluoroolefinsof the present invention may also be useful in stationaryair-conditioning and heat pumps, e.g. chillers, high temperature heatpumps, residential and light commercial and commercial air-conditioningsystems. In stationary refrigeration applications, the presentcompositions may be useful in equipment such as domestic refrigerators,ice machines, walk-in and reach-in coolers and freezers, and supermarketsystems.

When used as refrigerants, the combinations containing Z and Estereoisomers of hydrofluoroolefins of the present invention typicallywill include refrigeration lubricants, i.e. those lubricants suitablefor use with refrigeration, air-conditioning, or heat pump apparatus.Among these lubricants are those conventionally used in compressionrefrigeration apparatus utilizing chlorofluorocarbon refrigerants. Suchlubricants and their properties are discussed in the 1990 ASHRAEHandbook, Refrigeration Systems and Applications, chapter 8, titled“Lubricants in Refrigeration Systems”. Lubricants of the presentinvention may comprise those commonly known as “mineral oils” in thefield of compression refrigeration lubrication. Mineral oils compriseparaffins (i.e. straight-chain and branched-carbon-chain, saturatedhydrocarbons), naphthenes (i.e. cyclic paraffins) and aromatics (i.e.unsaturated, cyclic hydrocarbons containing one or more ringscharacterized by alternating double bonds). Lubricants of the presentinvention further comprise those commonly known as “synthetic oils” inthe field of compression refrigeration lubrication. Synthetic oilscomprise alkylaryls (i.e. linear and branched alkyl alkylbenzenes),synthetic paraffins and napthenes, and poly(alphaolefins). Lubricants ofthe present invention further comprise those that have been designed foruse with hydrofluorocarbon refrigerants and are miscible withrefrigerants of the present invention under compression refrigeration,air-conditioning, or heat pump apparatus' operating conditions. Suchlubricants include, but are not limited to, polyol esters (POEs) such asCastrol® 100 (Castrol, United Kingdom), polyalkylene glycols (PAGs) suchas RL-488A from Dow (Dow Chemical, Midland, Mich.), and polyvinyl ethers(PVEs). These lubricants are readily available from various commercialsources.

2. Blowing Agents

For polyurethane blowing applications the preferred combinations of thepresent invention will typically have boiling points between about −40°C. to 60° C. and be compatible with the A side, the B side or both andtypically are liquid at atmospheric pressure from about 10° C. to 50° C.and more preferably 30° C. to 40° C. and provide a foam with gooddimensional stability. The combinations have a low thermal conductivityand provide a foam with low thermal conductivity.

For the production of thermoplastic foams, the preferred combinations ofthe present invention will have boiling points less than the melt and/orglass transition temperature of the polymer resin, typically less thanabout 100° C., preferably between about −40° C. to about 10° C.

The process for preparing a foamed thermoplastic product is as follows:Prepare a foamable polymer composition by blending together componentscomprising foamable polymer composition in any order. Typically, preparea foamable polymer composition by plasticizing a polymer resin and thenblending in components of a blowing agent composition at an initialpressure. A common process of plasticizing a polymer resin is heatplasticization, which involves heating a polymer resin enough to softenit sufficiently to blend in a blowing agent composition. Generally, heatplasticization involves heating a thermoplastic polymer resin near orabove its glass transition temperature (Tg), or melt temperature (Tm)for crystalline polymers.

A foamable polymer composition can contain additional additives such asnucleating agents, cell-controlling agents, dyes, pigments, fillers,antioxidants, extrusion aids, stabilizing agents, antistatic agents,fire retardants, IR attenuating agents and thermally insulatingadditives. Nucleating agents include, among others, materials such astalc, calcium carbonate, sodium benzoate, and chemical blowing agentssuch azodicarbonamide or sodium bicarbonate and citric acid. IRattenuating agents and thermally insulating additives include carbonblack, graphite, silicon dioxide, metal flake or powder, among others.Flame retardants can include, among others, brominated materials such ashexabromocyclodecane and polybrominated biphenyl ether.

Foam preparation processes of the present invention include batch,semi-batch, and continuous processes. Batch processes involvepreparation of at least one portion of the foamable polymer compositionin a storable state and then using that portion of foamable polymercomposition at some future point in time to prepare a foam.

A semi-batch process involves preparing at least a portion of a foamablepolymer composition and intermittently expanding that foamable polymercomposition into a foam all in a single process. For example, U.S. Pat.No. 4,323,528, herein incorporated by reference, discloses a process formaking polyolefin foams via an accumulating extrusion process. Theprocess comprises: 1) mixing a thermoplastic material and a blowingagent composition to forma foamable polymer composition; 2) extrudingthe foamable polymer composition into a holding zone maintained at atemperature and pressure which does not allow the foamable polymercomposition to foam; the holding zone has a die defining an orificeopening into a zone of lower pressure at which the foamable polymercomposition foams and an openable gate closing the die orifice; 3)periodically opening the gate while substantially concurrently applyingmechanical pressure by means of a movable ram on the foamable polymercomposition to eject it from the holding zone through the die orificeinto the zone of lower pressure, and 4) allowing the ejected foamablepolymer composition to expand to form the foam.

A continuous process involves forming a foamable polymer composition andthen expanding that foamable polymer composition in a non-stop manner.For example, prepare a foamable polymer composition in an extruder byheating a polymer resin to form a molten resin, blending into the moltenresin a blowing agent composition at an initial pressure to formafoamable polymer composition, and then extruding that foamable polymercomposition through a die into a zone at a foaming pressure and allowingthe foamable polymer composition to expand into a foam. Desirably, coolthe foamable polymer composition after addition of the blowing agent andprior to extruding through the die in order to optimize foam properties.Cool the foamable polymer composition, for example, with heatexchangers.

Foams of the present invention can be of any form imaginable includingsheet, plank, rod, tube, beads, or any combination thereof. Included inthe present invention are laminate foams that comprise multipledistinguishable longitudinal foam members that are bound to one another.

In another embodiment, the present invention relates to blowing agentcombinations containing Z and E stereoisomers of hydrofluoroolefins asdescribed herein for use in preparing foams. In other embodiments theinvention provides foamable compositions, and preferably polyurethane,polyisocyanate and thermoplastic foam compositions, and method ofpreparing foams. In such foam embodiments, one or more of the presenthydrofuoroolefins with stabilizer combinations are included as a blowingagent in foamable compositions, which composition preferably includesone or more additional components capable of reacting and foaming underthe proper conditions to form a foam or cellular structure. Any of themethods well known in the art may be used or adapted for use inaccordance with the foam embodiments of the present invention.

The present invention further relates to a method of forming a foamcomprising: (a) adding to a foamable composition a combinationscontaining Z and E stereoisomers of hydrofluoroolefins of the presentinvention; and b) reacting the foamable composition under conditionseffective to form a foam.

3. Aerosol Propellants:

Another embodiment of the present invention relates to the use of thecombinations containing Z and E stereoisomers of hydrofluoroolefins asdescribed herein for use as propellants in sprayable compositions.Additionally, the present invention relates to a sprayable compositioncomprising the combinations containing Z and E stereoisomers ofhydrofluoroolefins as described herein. The active ingredient to besprayed together with inert ingredients, solvents and other materialsmay also be present in a sprayable composition. Preferably, thesprayable composition is an aerosol. Suitable active materials to besprayed include, without limitations, cosmetic materials, such asdeodorants, perfumes, hair sprays, cleaners, and polishing agents aswell as medicinal materials such as anti-asthma and anti-halitosismedications.

The present invention further relates to a process for producing aerosolproducts comprising the step of adding combinations containing Z and Estereoisomers of hydrofluoroolefins as described herein to activeingredients in an aerosol container, wherein said composition functionsas a propellant.

A further aspect provides methods of suppressing a flame, said methodscomprising contacting a flame with a fluid comprising a combinationscontaining Z and E stereoisomers of hydrofluoroolefins of the presentinvention. Any suitable methods for contacting the flame with thepresent composition may be used. For example, a combinations containingZ and E stereoisomers of hydrofluoroolefins of the present invention maybe sprayed, poured, and the like onto the flame, or at least a portionof the flame may be immersed in the flame suppression composition. Inlight of the teachings herein, those of skill in the art will be readilyable to adapt a variety of conventional apparatus and methods of flamesuppression for use in the present invention.

4. Fire Fighting Agents:

A further embodiment provides methods of extinguishing or suppressing afire in a total-flood application comprising providing an agentcomprising a combinations containing Z and E stereoisomers ofhydrofluoroolefins of the present invention; disposing the agent in apressurized discharge system; and discharging the agent into an area toextinguish or suppress fires in that area. Another embodiment providesmethods of inerting an area to prevent a fire or explosion comprisingproviding an agent comprising a combinations containing Z and Estereoisomers of hydrofluoroolefins of the present invention; disposingthe agent in a pressurized discharge system; and discharging the agentinto the area to prevent a fire or explosion from occurring.

The term “extinguishment” is usually used to denote complete eliminationof a fire; whereas, “suppression” is often used to denote reduction, butnot necessarily total elimination, of a fire or explosion. As usedherein, terms “extinguishment” and “suppression” will be usedinterchangeably. There are four general types of halocarbon fire andexplosion protection applications. (1) In total-flood fireextinguishment and/or suppression applications, the agent is dischargedinto a space to achieve a concentration sufficient to extinguish orsuppress an existing fire. Total flooding use includes protection ofenclosed, potentially occupied spaces such, as computer rooms as well asspecialized, often unoccupied spaces such as aircraft engine nacellesand engine compartments in vehicles. (2) In streaming applications, theagent is applied directly onto a fire or into the region of a fire. Thisis usually accomplished using manually operated wheeled or portableunits. A second method, included as a streaming application, uses a“localized” system, which discharges agent toward a fire from one ormore fixed nozzles. Localized systems may be activated either manuallyor automatically. (3) In explosion suppression, a combination containingZ and E stereoisomers of hydrofluoroolefins of the present invention isdischarged to suppress an explosion that has already been initiated. Theterm “suppression” is normally used in this application because theexplosion is usually self-limiting. However, the use of this term doesnot necessarily imply that the explosion is not extinguished by theagent. In this application, a detector is usually used to detect anexpanding fireball from an explosion, and the agent is dischargedrapidly to suppress the explosion. Explosion suppression is usedprimarily, but not solely, in defense applications. (4) In inertion, acombination containing Z and E stereoisomers of hydrofluoroolefins ofthe present invention is discharged into a space to prevent an explosionor a fire from being initiated. Often, a system similar or identical tothat used for total-flood fire extinguishment or suppression is used.Usually, the presence of a dangerous condition (for example, dangerousconcentrations of flammable or explosive gases) is detected, andcombination containing Z and E stereoisomers of hydrofluoroolefins ofthe present invention is then discharged to prevent the explosion orfire from occurring until the condition can be remedied.

The extinguishing method can be carried out by introducing thecomposition into an enclosed area surrounding a fire. Any of the knownmethods of introduction can be utilized provided that appropriatequantities of the composition are metered into the enclosed area atappropriate intervals. For example, a composition can be introduced bystreaming, e.g. using conventional portable (or fixed) fireextinguishing equipment; by misting; or by flooding, e.g., by releasing(using appropriate piping, valves, and controls) the composition into anenclosed area surrounding a fire. The composition can optionally becombined with an inert propellant, e.g., nitrogen, argon, decompositionproducts of glycidyl azide polymers or carbon dioxide, to increase therate of discharge of the composition from the streaming or floodingequipment utilized.

Preferably, the extinguishing process involves introducing a combinationcontaining Z and E stereoisomers of hydrofluoroolefins of the presentinvention to a fire or flame in an amount sufficient to extinguish thefire or flame. One skilled in this field will recognize that the amountof flame suppressant needed to extinguish a particular fire will dependupon the nature and extent of the hazard. When the flame suppressant isto be introduced by flooding, cup burner, test data is useful indetermining the amount or concentration of flame suppressant required toextinguish a particular type and size of fire.

5. Solvent:

The ideal hydrofluoroolefin, suitable for solvent applications, shouldhave bp between 21-60° C. The product should be chemically stable incontact with metals, doesn't swell upon exposure to various plastic suchas acrylonitrile butadiene styrene, PVC, polybutyelene tetraphathlate,polyethylene HD, polyethylene LD, polymethyle methacrylate,polyethylene, high impact polystyrene, polystyrene crystals, polystyrene1160, polypropylene, polyamide 11, polycarbonate, polyvinylidenefluoride, polyetehrer block amide; or elastomeric material such asstyrene butadiene 6510, ethylene propylene EP710, hydrogenatednitrile7DT1566, polychloroprene N658, polyacrylates DA 65, hyplalonDH70, fluorocarbon df, nitrile PB701, silicone SL1002, polyisoprenepolybutadiene c6514, teflon 62945R.

For all the application described in this invention, the compositionscontaining a combination of Z and E stereoisomers of hydrofluoroolefin,could be use in combination with a stabilizer or stabilizers selectedfrom free radical scavengers, acid scavengers, oxygen scavengers,polymerization inhibitors, corrosion inhibitors and combinationsthereof.

What is claimed:
 1. A method of preparing a combination of Z and Eisomers of a hydrofluoroolefin comprising from a trace up to about 30%by weight of the E isomer from a combination having more than about 30%by weight of the E isomer comprising reactive distillation of acombination of Z and E isomers of a hydrofluoroolefin having more thanabout 30% by weight of the E isomer followed by distillation.